Recently, as a successor to the flash memory, a resistive memory device including a variable resistance element as a memory element has drawn attention. Here, the resistive memory device shall include several kinds of devices including the strictly resistive RAM (ReRAM) and the phase change RAM (PCRAM). The ReRAM includes, as the recording layer, a transition metal oxide and stores its resistance value state in a non-volatile manner. The PCRAM includes, as the recording layer, a material such as chalcogenide and uses the resistance value information of its crystal state (conductor) and amorphous state (insulator).
The resistive memory device comprises a memory cell array. The memory cell array has memory cells disposed at intersections of bit-lines and word-lines. Each memory cell includes a variable resistance element. The memory cell array may use the characteristics of the variable resistance element to select one of the memory cells. In addition, an alternating stack of the bit-lines and the word-lines and a three-dimensional array of the memory cells may achieve the high density memory cell array.
In the high density memory cell array, a select transistor for selecting one of the bit-lines and one of the word-lines included in the memory cell array may also have a stacked structure similarly to the memory cell array. Unfortunately, if the memory cell array becomes highly densified, increasing the number of necessary select transistors, the arrangement and the manufacturing method of the select transistors become complicated.